Track-type machines are in widespread use in construction, mining, forestry, and other similar industries. The undercarriage of such track-type machines utilizes track assemblies, rather than wheels, to provide ground-engaging propulsion. Such track assemblies may be preferred in environments where creating sufficient traction is problematic, such as those frequently found in the industries identified above. Specifically, rather than rolling across a work surface on wheels, track-type machines utilize one or more track assemblies that include an endless loop of coupled track links defining outer surfaces, which support ground-engaging track shoes, and inner surfaces that travel about one or more rotatable track-engaging elements, such as, drive sprockets, idlers, tensioners, and rollers, for example.
Typical track chain assembly designs include a track pin either fixedly or rotatably connected to a pair of chain links and a bushing rotatably positioned between the links and about the track pin. Such track chain assemblies can operate in extremely adverse environments in which track joints may be exposed to various abrasive mixtures of water, dirt, sand, rock or other mineral or chemical elements.
Track seals are disposed between the components of a track chain of a tracked undercarriage in order to seal the track chain against dirt, mud, and debris while retaining lubricants in the track chain. The failure of a seal within a track chain can accelerate wear and cause early failure of a portion of the track chain.
A common type of seal used in track chains is referred to as a “can” seal. A can seal often includes a “lip” supported by a can and a load ring engaging the can. The surface defining a seal cavity interacts with the load ring to apply a force to the can and lip combination. The lip engages a sealing surface of an adjacent component. The can seal, the surface of one component defining the seal cavity, and the sealing surface of the adjacent component cooperate together to provide a sealed interface to retain lubricant within the assembly and protect against dirt, mud, abrasive materials, debris and other contaminants. Examples of such can seals are shown and described in U.S. Patent Application Publication No. US 2007/10267821; U.S. Pat. Nos. 6,739,680; 5,794,940; and 4,094,516; and International Application Publication No. WO 2008/093160 A1.
One cause of failure of current can-type seals is known in the art as “heel under.” Heel under describes the situation where debris is ingested between an outer surface of the load ring and the seal cavity. The debris builds up and can cause the load ring to rotate or move out of position against the can resulting in the failure of the can seal and leakage of lubricant.
U.S. Patent Application Publication No. US 2011/0254364 is entitled, “Seal Assembly for Track Pin Joint Assembly,” and is directed to a seal assembly which can be incorporated into a track pin joint assembly including a pin defining a longitudinal axis, a first member and a second member both coaxial with the pin about the longitudinal axis. A seal assembly including a seal ring and a load ring is disposed in a seal cavity and sealingly engages the first member and the second member. At least one of a load ring engagement surface of the first member and an axial segment of a first member engagement surface of the load ring includes a convex rounded portion extending over at least half the axial length thereof. The load ring may include a neck portion extending from the main body at a first angle to an axial segment of a can engagement surface in an uninstalled state with the neck extending from the main body at a second angle to the axial segment of the can engagement surface in an installed state. Although such a seal assembly is effective to help reduce the incidence of heel under failures, there is a continued need in the art to provide additional solutions for a seal assembly which can maintain adequate seal pressure and help resist seal failures, such as, heel under.
It will be appreciated that this background description has been created by the inventors to aid the reader, and is not to be taken as an indication that any of the indicated problems were themselves appreciated in the art. While the described principles can, in some respects and embodiments, alleviate the problems inherent in other systems, it will be appreciated that the scope of the protected innovation is defined by the attached claims, and not by the ability of any disclosed feature to solve any specific problem noted herein.